crusade has 9 distinct synonyms spread across 2 of its 4 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a series of actions advancing a principle or tending toward a particular end
“he supported populist campaigns”
any of the more or less continuous military expeditions in the 11th to 13th centuries when Christian powers of Europe tried to recapture the Holy Land from the Muslims
go on a crusade; fight a holy war
Synonyms, antonyms and the broader and narrower relations for crusade come from Princeton University’s WordNet. Full sources and licences.